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H. G. GElSSI NGER. ELECTRIC CONTACT THERMOSTAT. APPLICATION FILED 1AN.'19.\s1a.

1 ,3 1 5, 6O 1 Patented Sept. 9, 1919.

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Mm /W+%m York and State of New and 40 contacts other than that of the air.

closely approximated the ideal condition,

45 posure to the air STATES PATENT orrion.

HARRY G. GEISSINGER, or NEW YORK, N. Y. TRUSTEE, or DETROIT, MICHIGAN To all whom it may concern:

Be it known that LHHARRY G. GEIssINonR,

a citizen of the United States of America, residing at New York, in the county of New York, have invented certain new and useful Improvements in Electric-Contact Thermostats, of which the following is a specification, reference being had therein to the accompanying drawings. e invention relates to thermostats of that type'in which the electrical contact is made or broken by the lateral deflection of an arched element in cooperation with a chord or tie element having a different ooefficient of expansion. It is the object of the present invention to overcome certaindefects of constructions of the type heretofore devised and to render the instrument more sensitive and accurate in its operation and simple in its construction. The invention therefore comprises various features of construction as hereinafter set forth.

In the drawings: Figure 1 is aplan view through the instrument;

Fig. 2 isa longitudinal section thereof;

Fig. 3 is a side elevation.

he principle on which the construction is based is the deflection of the arch element by differential expansion due solely to the temperature which is to be controlled. Accuracy is therefore only obtained where there is eedom for movement without frictional or other resistance; where the expansible ele- IfiBIltS areexposed to free contact with the air; and where the temperature of these elements -is unaffected either by independent heat generation or' conduction to .or from I have first, by eliminating friction and providing perfect freedom of action without mechanir cal restraint; second, by providing full exof all the surface of the expansible elements, of the one by another; third, by providing suflicient area and mass in the element which forms a portion of the electrical circuit to 5 quickly dissipate whatever heat is elect-rically generated; fourth, by 'interposing thermal insulation between the elements and the base on whlclrt ey are mounted to avoid transfer of heat from the one the other;

\ Specification of Letters Patent.

avoiding any shielding ASSIGNOR TO THE PEQPLES STATE BANK,

, A CORPORATION OF MICHIGAN.

ELECTRIC-CONTACT THERMOSTAT. v

' Patented se ta, 1919.

Application filed January 19, 1918. Serial No. 212,804.

fifth, by providing a linkage between the elements having diflerent coefficients of expansion, which secures accuracy in movement without necessitating a high degree of mechanical perfection.

A is a base or supporting frame, which is provided with projecting lugs B and B for the securing of the ends of a pair of chord elements C and C arranged parallel to each other and extending in a plane parallel to the base. The opposite ends of these chord elements are connected to each other by a yoke D, which has a flexible portion E for attaching it to the base, so that the chord elements will be maintained in the same plane while being free to adjust themselves in said plane to compensate for expansion and contraction. F is an arch element arrangedintermediate the'chord elements 0 and C in substantially the same plane and differing therefrom as to its coefficient of expansion, the arch being greatly exaggerated for clearness.

One end of this arch engages a V-shaped bearing G which is pivotally connected at H to the yoke D and preferably extends through an aperture in the portion E. This aperture may be formed bv striking out lugs or ears I from the member E, which act as guides for the ends of the V-shaped bearing G and for the end of the I arch member F engaged therewith. Thus the bearingG is self-alining and at the same time disengagement of the arch is prevented. J is the electrical contact which cooperates with the arch member in the closing and opening of the electrical circuit, said contact being mounted upon the base A and insulated therefrom by the insulating member The.contact is preferably in the form of a screw passing through the insulator K and adjustable longitudinally by engaging nuts L upon opposite sides of the. insulator. M is an insulated terminal post, which is connected with the contact member J through the link N.

It is one of the objects of the invention to provide an adjustment between thearch and the contact J, which is independent of any adjustment of the contact screw. This has the advantage of greater accuracy in setting, as the bearing surface of the contact is seldom inexact axial alinement with the screw and therefore! a rotation of the latter will cause a more or' lss eccentric movement of the contact. This in turn will produce a lateral movement relative to the contact on the arch member, and as this is seldom in a plane exactly perpendicular to the axis of the screw accurate adjustment by rotation of the screw is difficult. I have avoided the difliculty by providing means for adjusting one end of the arch in a direction perpendicular to the plane there,

of, which adjustment will produce a relative movement between the contact on the arch and the fixed contact J. It is essential in this lateral adjustment of the arch to avoid any variation in the length between the ends of the arch, as such variation would change the curvature. It is also essential to provide means for varying the curvature of the arch which is independent of this lateral adjustment, and both of these adjustments are provided for by the construction as follows: E is a lug intermediate the lugs B and B, which is provided with an oblique or wedge surface forming a bearing for a cooperating wedge member 0. The opposite face of the wedge member O is in a plane perpendicular to the plane-of the arch and chord elements and forms a bearing for an adjustable block P, which is notched to engage the end of the arch element. Q is a screw passing through a slot in the wedge element 0 and engaging a threaded bearing in the base A, so as to form a means for adjusting the wedge relative thereto. R is a screw engaging the base and bearing against the block P so as to form a means of adjusting the latter relative to the wedge. Thus by adjusting the screw Q the wedge will be moved to change the curvature of the arch. while by adjusting the screw R the arch will be deflected laterally without altering this cur'vature. It is necessary to hold the block P in contact with the screw R and also in cont-act with the face of the wedge member. For this purpose I have provided a pair of links S S on opposite sides of the lug B and the wedge O and block P. These links are loosely connected by a piIrT which engages a notch in the lug B and are also connected by a pin I engaging a notch in the block P. The links S S are bent-into the form of a bellcrank lever and at the end of the bent portion is a pin V forming a bearing for a spring \V which is anchored to the lug B The arrangement is such that the tension of the spring W, operating upon the pin V, will first draw the pin U against the block P to hold the latter firmly against the wedge and the wedge against the lug B and also by fulcruming about the pin T will yieldably press the block P against the screw R. Thus a single spring maintains the block P against both of its bearings and insures the maintenance of relative position. of parts when once adjusted.

swing the arch toward or To make the bearing and block P selfalining, instead of providing it with a flat face for contact with the wedge 0, it is preferably formed with a V-face so as to rock upon a vertical axis. Thus any inaccuracy either in the notch in the hearing or at the end of the arch member will be compensated for automatically.

In use, the instrument is adjusted by first adjusting the screw Q which actuates the wedge E, thereby moving the block P .toward or from the arch element to alter the curvature thereof. During this adjustment the block P will be maintained perpendicular to the plane'of the elements and in the same relative position to the adjusting screw It, its only movement being a rectilinear one parallel to the plane of the. arch. After the curvature of the arch has been thus adjusted the distance between the arch and the contact point J may be adjusted by operation of the screw R. This, by movement of the block P upon the faceof the wedge 0 will from the contact J without altering the curvature of the arch. In both of these adjustments the block P is held firmly against its hearing by the tension of the spring \Vywhich cooperates with the links S and S and pins T, U; V, and presses the block both against the screw R- and the face of the wedge.

In operation, the air of the room in which the instrument is located is free to come into contact with both faces of each of the ele ments C C and F, and as these elements are in substantially the same plane they will not in any way shield or interfere with each other. \Vhen there is a change in temperature, causing either expansion or contraction of the elements C and C the yoke ends 0 said elements are free to move relative to the base in their common plane by the flexing of the link E. On the other hand. since the corresponding extremities of the arch and chord elements may not move relatively and they. differ as to their coefiicients of expansion, a change in temperature can only result in a lateral deflection or change in curvature of the arch so as to adjust the same into or out of contact with the contact member J. \Vhen contact is established whatever heat is electrically generated will be quickly distributed by conduction and dissipated through the large air-exposed surface of the member F. As a consequence the opening and closing of the electrical circuit will correspond accurately to predetermined temperature changes in the air which bathes the elements C C and F.

Where the elements of the thermostat are mounted upon a metal body or frame in good heat conducting relation thereto there will be a lag in operation due to the transfer of heat between the elements and frame. To avoid this objectionable result I have interous ways, but as specifically shown X is a heat insulating member arranged between the flexible member E- and the base A, and X is a heat insulating member between each of the chord elements C and C and the lugs B and B to which they are secured. Thus the transfer of heat between the base and the elements of the thermostat is greatly slowed by the members and X.

What I claim as my invention is:

1. In an electric contact thermostat, the combination with an arch element and chord elements arranged in substantially the same plane, of means for maintaining the chord elements constantly in their plane, a contact member in fixed relation to said plane, and means for laterally adjusting said arch element in relation to said contact member.

2. An electric contact thermostat, comprising an arch element and a air of cliord elements arranged in substantially the same plane, a base on which said elements are mounted, means for connecting the chord elements to said base to maintain the same constantly in the same. plane, an electric contact member mounted on said base and extending into proximity to said arch element, and means for adjusting said arch element laterally toward or from said contact memher and without altering the curvature thereof.

3. An electric contact thermostat, comprising a base, an arch element and a pair of chord elements arranged in substantially the same plane, means for connecting the chord elements to said base to maintain them constantly in the same plane, a yoke connecting the adjacent ends of the chord elements providing a bearing for the rocking engagement of one end of the arch element, a bearing for the opposite end of said arch element, means for independently adjusting said bearing longitudinally of the arch to alter the curvature thereof and laterally, and a contact normally fixed in relation to the base, toward and from whichsaid arch is moved by the lateral adjustment of said bearing.

-l. An electric contact thermostat, comprising a base member, an arch element and a air of chord elements arranged in substantially the same plane, bearings on said base to which-one end of each of said chord elements is rigidly attached, a flexible connection between said base and the opposite ends of said chord elements for maintaining the same in a fixed plane while permitting adjustment in said plane. a yoke between the free ends of said chord elements formin a bearing for one end of the arch element, 2

7 block forming a bearing for the opposite end adjusting said wedge on said fixed bearing to shift said block and alter the curvature of the arch, and a contact member normally fixed on the base, toward and from which said arch is adjusted by the lateral movement of said block on said wedge.

5. An electric contact thermostat, comprising a base, an arch element and a pair of chord elements arranged in substantially the same plane, means for attaching one end of each of the chord elements rigidly to said base, a flexible connection between the opposite ends of said chord elements and said base forv maintaining a fixed plane of said elements while permitting adjustment in said plane, a yoke between said chord elements forming a bearing for one end of the arch element, a block forming a bearing for the opposite end of said arch element, a wedge having one face perpendicular to the plane of said elements, forming a bearin for said block, an inclined bearing on said base for the opposite face of said wedge, in-

dependent means of adjusting said wedge upon its bearing on the base and for ac justing said block upon said wedge, and means for yie'ldably pressing said block against gaid wedge and the adjustment means there- 6. An electric contact thermostat, comprising a base, an arch element and a air of chord elements arranged in substantia ly the same plane, one end of each of the chord elements being rigidly attached to said base, a flexible connection between the opposite ends of said chord elements and said base permitting adjustment thereof to maintain the plane of said elements, .a yoke connecting'the adjustable ends of said chord elements, a bearing for said arch element on said yoke, a wedge having an oblique bearing on said base and provided with a face perpendicular to the plane of said elements, a screw for adjusting said wedge toward or from said base, a block forming a bearing for-the opposite end of said arch element and slidably engaging the perpendicular face of said wedge, a screw in said base for adjusting said block upon said wedge, a pair-of links embracing said block and wedge, and a tensioning device operating through said links for holding said block against said wedge and also against the adjusting screw for the block.

7. In an electric contact thermostat, an arch element and a chord element having different coefficients of expansion, arralrzlged in substantially the same plane, a a

, j mounting for said elements having a rigid connection Wlt-hODQ end thereof and a flexible connection to the opposite end.

8. An electric contact thermostat, comprising an arch element and a pair of chord elements arranged in substantially the same plane, the arch element being intermediate the chord elements, a connection between the corresponding ends of said elements, and a self-alining bearing for said arch element upon said connection.

9. In an electric contact thermostat, an arch element and a pair of chord elements arranged insubstantially the same plane, connections between the corresponding opposite ends of said elements, and self-alining hearings on said connections for said arch elements.

10. In an electric Contact thermostat, an arch element and a pair of chord elements arranged in substantially the same plane with the arch element centrally between said chord elements, connections between the corresponding opposite ends of said elements, means for adjusting one end of said arch element On its connection, a mounting for-said elements rigidly attached to one of the connected ends thereof, and a flexible connection between said mounting and the opposite connected end of said elements to permit movement thereof only in their plane.

11. In an electric contact thermostat, an

arch element and a chord element having different coefficients of expansion, arranged in substantially the same plane, a base or mounting for said elements having a rigid connection therewith at one end, a flexible connection between the opposite end of said elements and said base, permitting freedom of movement in .their common plane, and a bearing for said arch element adjustable on said mounting in said common plane.

12. An electric contact thermostat, comprising an arch element and a pair of chord elements arranged on opposite sides thereof in substantially the same plane, a mounting having a rigid connection to one end of each of the pair of chord elements, a yoke connecting the opposite ends of the pair of chord elements, a flexible connection between said yoke and the mounting for maintaining said chord elements in the same plane while permitting movement of the yoke in said plane, a V-shaped bearing pivotally connected to said yoke and having a self alining engagement with the end of said arch element, and a V-shaped bearing having a self-alining engagement with the opposite end of said arch element, and means for adjusting the latter bearing to alter the curvature of the arch.

In testimony whereof I afiix my signature.

HARRY G. GEISSINGER. 

